1. Field of the Invention
The present invention relates generally to scanning probe microscopy and, more particularly, to an environmental cell that is used with a scanning probe microscope. In accordance with one embodiment of the present invention, an environmental cell is provided for a scanning probe microscope in which a probe comprising the scanning probe microscope is scanned and a sample being studied is held stationary.
2. Description of the Prior Art
In a scanning probe microscope (SPM), it is possible to scan a sample and hold the probe stationary. Alternatively, it is possible to scan the probe and hold the sample stationary.
In the type of SPM in which the sample is held stationary, a sharp probe is typically scanned over a surface of the sample in a raster scan motion while the probe is maintained in a predetermined relationship to the surface. A sensing system, together with a feedback circuit and electromechanical transducer, is used to maintain the predetermined relationship between the probe and surface. A three-dimensional image of the surface may then be created by displaying the motion of the probe on a display such as a computer screen. The sharper the probe of an SPM, the higher the horizontal resolution of the image will be. Scanning the probe has substantial advantages, because the sample size can be changed without unwanted effects on the feedback circuit coupled to the sensing system. FIG. 1 illustrates the primary components of a known scanning probe microscope of the type known as an atomic force microscope (AFM) having a scanned probe. In an AFM the x, y, z electromechanical transducers are disposed in an AFM “head.”
There are many different types of probes and sensing systems that can be used in an SPM. For example, if the probe and sample are electrically conductive, the current flow between the probe and sample may be monitored and used to establish a predetermined distance between the probe and surface of the sample. This type of scanning probe microscope is generally known as a scanning tunneling microscope (STM). The most commonly used type of SPM is the AFM. In an AFM, the relationship between the probe and surface of the sample is established using a force sensor comprising the sensing system. The probe is raster scanned in the X-Y plane, and the Z position of the probe is controlled by the sensing system together with a feedback circuit and electromechanical transducer.